Lemony Spatchcocked Chicken

Adapted from Martha Stewart's "Roast Spatchcocked Lemon Chicken"

Servings: 4

Add about 3.5 or 4 quarts of water into a 5 quart stock pot.
Add all of the brine ingredients to the water and mix until combined. Note: you may need to tweak this based on how it tastes to you.
Place the whole raw chicken, removing any giblets, into the brine solution until it is completely submerged.
Add a few cups full of ice to the stock pot, cover, and store in the fridge for 2-4 hours.

Preheat oven to 425 degrees
Slice about 5 or 6 lemons and arrange them into a layer in a roasting pan or on a cooking sheet, setting aside 3 or 4 slices for later.
Slice onion and scatter across the bed of lemons
Remove the chicken from the brine, which can be discarded
Using kitchen shears, remove the chicken backbone by make two clean cuts on either side. Set this aside for use later if you wish to use it to make chicken stock (highly recommend).
Place the bottom of your palms on the chicken breast and, grabbing the back side of the chicken, splay the chicken out so that it will lay flat.
Season the outside of the chicken with a pinch of salt, a pinch of pepper, and chopped rosemary, then place the chicken breast side up on top of the bed of lemon slices.
Using your fingers, separate the chicken skin from the breast meat so that becomes almost like a pocket. To this add the 3 or 4 lemon slices that you set aside in a previous step. Optional: if you also want to add a couple small pats of butter under the skin (I do this with turkey), don't let me tell you not to. I mean, it's butter.
Place into the oven on the middle rack and roast for approximately 45-60 minutes, or until the internal temperature reaches 160 degrees.
Remove the chicken from the oven and let rest for 5-10 minutes.
Carve and serve!